The algorithm that simulates random polycondensation has been developed in previous work. The simulations yield accurate estimates of gel points, the extent of cyclization, cycle rank, and sol distributions. In the experiments, triols with oxypropylene repeating units were condensed with hexamethylene diisocyanate. The number average molecular weight (MW) of the triol was 3000 and the functionality was about 2. 95. In this paper the effects of MW distribution and side reactions on extents of cyclization, sol structures and gel points are illuminated.